1. Field of the Invention
This invention relates to an improved punching press, and more particularly, to a punching press wherein the procedures of pressing, punching, and pushing the product apart from dies can be completed during one turn of a crank shaft.
2. Description of the Prior Art
Most conventional presses adapt a crank shaft and a connecting means to drive a flywheel to convert the rotational energy into reciprocating power, in which the crank may be in the form of a single crank-pin type or a multiple crank-pin type. FIG. 1a shows a crank being usually used in the conventional presses which has a crank pin 3, two crank arms 2 and a crank shaft 1. The crank pin 3 is coupled with one end of a connecting rod (not shown) so as to make an eccentric rotation, another end of the connecting rod is engaged with a screw rod attached to a slide so that the slide may move reciprocally in downward or upward direction so as to perform the procedure of metal deformation. Additionally, the crank arms are usually provided with a counter balance weight so as to make the rotation of the crank shaft 1 smooth. However, an outstanding disadvantage of the previous presses is that only one power stroke will be generated for one revolution. Therefore, it is impossible to finish a product which needs to be both punched and pressed in one operation.
FIG. 1b shows a crank for the conventional press having two crank pins, four crank arms 5 and a crank shaft 1. Although the presses provided with the crank may generate two power strokes during one turn of the crank shaft, the cost, occupied space, complexity of construction and possibility of damage is also increased.